[amidgeha]

Generator System Performance

The Engine Control Module (ECM) uses the generator turn ON signal circuit to control the generator. A high side driver within the ECM allows the ECM to turn the generator ON and OFF. When Generator operation is desired, the ECM sends a 5 volt signal to the voltage regulator via the generator turn on signal circuit. This causes the voltage regulator to begin controlling the generator field circuit. Once the Generator is enabled by the ECM, the voltage regulator controls generator output independently of the ECM. Under certain operating conditions, the ECM can turn Off the generator by turning Off the 5 volt signal on the generator turn on signal circuit. The ECM sets the OBDII when the generator does not respond to the ECM ON signal.

Cause:
Faulty Generator (Alternator)
Generator harness is open or shorted
Generator circuit poor electrical connection

Symptoms:
Check engine light